Re: Pahole/BTF issue with __int128

["Alexis Lothoré" <alexis.lothore@bootlin.com>]

Hi Tony,
thanks a lot for the prompt answer !

On Wed May 7, 2025 at 10:39 PM CEST, Tony Ambardar wrote:
> On Wed, May 07, 2025 at 10:02:51PM +0200, Alexis Lothoré wrote:
>> Hello,

[...]

> Hi Alexis,
>
>> Am I missing some constraint or limitation that would prevent the case 2
>> function from being described with BTF info ? If not, any advice about how
>> to debug this further ?
>> 
>
> I suspect this might be related to an issue I ran into where pahole may
> mis-encode types larger than register-size [1]. Out of curiosity, could
> you try rebuilding and using a pahole with my latest patch [2]?
>
> 1: https://lore.kernel.org/dwarves/20250410083359.198724-1-tony.ambardar@gmail.com/
> 2: https://lore.kernel.org/dwarves/20250502070318.1561924-1-tony.ambardar@gmail.com/

I gave a try to your patch on top of pahole 1.30, and indeed it seems that
my issue is fixed with your solution. I now have some BTF info for my
bpf_testmod_test_struct_arg_11 func:

  [...]
  [370] FUNC_PROTO '(anon)' ret_type_id=6 vlen=6
          'a' type_id=10
          'b' type_id=10
          'c' type_id=10
          'd' type_id=10
          'e' type_id=5
          'f' type_id=10
  [371] FUNC 'bpf_testmod_test_struct_arg_11' type_id=370 linkage=static
  [...]

I also did some quick tests around Alan's request in your series, I'll
report to your series' thread.

Thanks for the help !

Alexis


>
> Cheers,
> Tony
>
>> Thanks,
>> 
>> Alexis
>> 
>> -- 
>> Alexis Lothoré, Bootlin
>> Embedded Linux and Kernel engineering
>> https://bootlin.com




-- 
Alexis Lothoré, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com